1. Field of the Invention
The present invention relates to a slide fastener, and more particularly to a lockable slider for slide fastener.
2. Prior Art
There has been proposed a lockable slider of the type described which includes a built-in locking mechanism comprising a cylindrical plug rotatably received in a cylindrical bore in a slider body and adapted to be rotated by a separate key, a locking member having one end held in engagement with a slanted cam face formed on the lower surface of the cylindrical plug and the other end bent downwardly to provide a locking pawl, and a compression coil spring urging the one end of the locking member and the cylindrical plug upwardly so that the locking pawl is brought into locking engagement with a pair of coupling element rows in response to the rotation of the cylindrical plug. The cylindrical plug has a depending shaft adapted to extend through an aperture in the one end of the locking member into a cylindrical opening in the coil spring. With this arrangement, the locking mechanism must be assembled before it is mounted in the slider body with the result that automated assembling is difficult to achieve. The cylindrical bore has a stopper projecting inwardly from the inner peripheral surface for being slidably received within a peripheral recess formed in the cylindrical plug, the opposite ends of the recess confining the degree of rotation of the cylindrical plug. The assembling of the locking mechanism in the slider body involves the delicate and carefull operation of inserting the cylindrical plug into the bore with the requirement of positioning the cylindrical plug in an accurate angular position relative to the bore. It has accordingly been highly difficult to automate the assembling of the complete slider. Furthermore, the stopper allows the cylindrical plug to rotate in only one direction for locking or unlocking the slider to the pair of coupling element rows so that an operator needs to be careful not to turn the cylindrical plug in the wrong direction, or else either the key or the locking mechanism would be damaged or sometimes broken.